Closing Mass Balances Through Speciation of III-V Etching Products
Research Report Highlight
Report details the use of atmospheric gas-phase mass spectrometry (AGP-MS), and inductively-coupled plasma mass spectrometry (ICP-MS) to close a mass balance of GaAs.
FinFET device development can be advanced by III-V materials because they possess higher carrier mobilities than Si or Ge. Reaction products from cleaning and patterning III-Vs can remain in the liquid phase, become solids or evaporate as gases. Because etching products contain toxic elements such as As, In, and Sb, speciation under industrial processing conditions is important to understand and characterize. This report details the use of atmospheric gas-phase mass spectrometry (AGP-MS), and inductively-coupled plasma mass spectrometry (ICP-MS) to close a mass balance. The total arsenic concentration in the gas phase above 28.9 M HF, 0.6 M aqueous HF and an etching solution containing 6 M HCl and 1 M H2O2 was calculated to be between 1 and 2 ppm, using N2 as a reference. Using the concentration above 0.6 M HF, an As mass balance was closed within approximately 1 nmol. Future work is planned to close mass balances on industrially relevant processes and improve our understanding of III-V etching mechanisms.